Gas chromatographic analysis of the volatile oil of the leaf oil of lodgepole pine from the Rocky Mountains showed 1-β-phellandrene (34%) and 1-β-pinene (30.5%) as major components. Lesser amounts of α-pinene (6.5%), myrcene (3%), cis-ocimene (2.5%), 3-carene (1.5%), terpinolene (1%), γ-terpinene (0.3%), α-terpineol (4%), terpinen-4-ol (0.5%), estragole (0.5%), bornyl acetate (0.5%), linalool (0.3%), a mixture of cadinene isomers (5%), cadinol and muurolol isomers (1.5%), nerolidol (0.6%), and tentatively identified camphene, α-phellandrene, limonene, isopulegol, camphene hydrate, citronellol, bisabolol, and cis- and trans-farnesol were recorded. In addition, hex-2-en-1-al (1.5%) and cis-hex-3-en-1-ol (1%) were isolated, but these may be artefacts because the leaves had to be cut to obtain a high yield of oil. The variation in the relative amounts of terpenes in leaves at different heights on a tree was small. Quantitative analysis of 10 samples per population showed a relatively high tree-to-tree variation, but similar mean values for populations in the Bragg Creek – Kananaskis – Eisenhower Junction area of Alberta. Small, but possibly significant differences were recorded for the samples from the Cypress Hills. Populations north of Lake Louise Station to Jasper, Hinton, and Edson were found to contain a few individuals with terpenes characteristic of jack pine. This indicates that the effects of introgression of lodgepole and jack pine can be detected further southwest than previously reported.